The present invention relates to an open fireplace of the kind which includes a fuel-carrying device and which enables the fire to be seen from all directions, and which further includes a generally vertical smoke duct whose bottom orifice is located above the fuel, and an air supply duct.
A fireplace of this general kind is known from GB-A-2,152,206. In the case of this known apparatus, the smoke duct or chimney is terminated with a conically widening canopy. In order to obtain an effective draught in fireplaces of this kind, it is necessary for the distance between the fire and the narrow smoke duct to be short, so that the temperature of the smoke in the chimney will be high. The conical part of the known fireplace introduces a large volume in the lower part of the smoke duct and increases the distance to the narrower part thereof. The temperature of the smoke or combustion gases in the smoke duct will therewith be lower and the draught poorer. In order to compensate for this, it is necessary to reduce the distance between the conical part of the smoke duct and the fire, meaning that not all of the fire will be visible to all occupants of the room. Thus, the comfort aspect essential with this type of fireplace, namely the possibility for all occupants to see the fire, is lost.
Furthermore, in the case of this known fireplace construction the air of combustion is taken from the surrounding room, meaning that the warm air present around the fire will pass out through the smoke duct pipe, or chimney. People sitting around the fire will therefore feel a cold draught coming from behind. The known fireplace construction also has low efficiency with regard to heat economy.
FR-A1-2,692,969 also describes a fireplace construction having a conical canopy which can be raised and lowered. The air of combustion is delivered via the fire grate.
This fireplace construction functions effectively when the conical canopy is lowered and supply air is sucked in via the grate. When the canopy is raised, however, the distance between the inlet orifice of the smoke duct and the supply air duct will be too great to generate a subpressure in the supply air duct. This subpressure namely decreases with the square of the distance. Air of combustion will thus be taken from the surrounding room. The conical fume canopy also introduces a larger volume which lowers the temperature of the smoke and impairs the draught.